Project 4: Project Summary/Abstract Residents who live near the Olin Superfund site (within the Mystic River Watershed) are worried because there was a cancer cluster in their community and their water contains N-nitrosodimethylamine (NDMA), a potent carcinogen in animal models. Policy decisions depend not only on knowing if NDMA can cause cancer, but we also need to know about how gene-environment interactions impact disease risk. NDMA is known to be potently carcinogenic in animal models, but little is known about how genetic factors modulate NDMA's effects on DNA damage, mutations and cancer. Here, we focus on Aag and Mgmt, the two genes that together are responsible for repairing more than 80% of the NDMA-induced DNA lesions. Here, we propose to exploit innovative mouse models with varied DNA repair capacity to learn how Aag and Mgmt impact susceptibility to NDMA-induced mutations and tumors. Specific Aim 1 is to reveal the impact of Aag and Mgmt on NDMA- induced tissue damage. Project 5 we will reveal systems level early after exposure. Among other endpoints, we will use our recently developed CometChip to measure DNA damage. For Specific Aim 2, we will collaborate with Project 3 to study mutations and we will use our RaDR mice for fluorescence detection of large-scale sequence rearrangements mediated by homologous recombination (an important class of mutations). We will also quantify tumor burden so that we can relate early responses to downstream consequences. For Specific Aim 3, we will compare the susceptibility of juvenile versus adult animals to NDMA-induced genomic instability and cancer. For Specific Aim 4, we will study long-term low-dose exposure to NDMA in water, and we will include NDMA levels that reflect environmental levels based on the findings of Project 1 and Project 2. Project 4 will be supported by Core A and Core D for support of personnel in terms of enrichment activities and professional development. Project 4 will also be supported by Core B to communicate results to Stakeholders, including a visit to the EPA and meetings with representatives from the Massachusetts Department of Public Health. Project 4 will also work closely with Core C to help develop materials for communicating to the local community as well as State and Federal Stakeholders. Taken together, in collaboration with Projects 1, 2, 3, and 5, Project 4 plays the exciting role of unifying key cancer related endpoints into an integrated whole that promises to yield insights into genetic risk factors (impacting risk assessment), to give rise to deeper understanding of the mechanisms of disease progression (which can ultimately open doors to new opportunities for prevention and mitigation), to improve our understanding of the impact of NDMA on a potentially vulnerable window of susceptibility, to yield mutational and proteomic biomarkers that predict disease susceptibility, and to reveal the real-world impact of NDMA on health under conditions that reflect those that are present in the Mystic River Watershed.